The objective of this research is to determine mutagenic and/or cytotoxic effects of alcohol on the chromosomes of an inbred strain of mice (C57B1/6) demonstrated to prefer alcohol. Two groups of mice, each consisting of twenty adult mice (90 days of age) will be exposed to 10 percent forced alcohol consumption. One group will receive the alcohol for six months; the second group will be given alcohol for twelve months. From each of these mice and from twenty control animals (not drinking alcohol) bone marrow and spermatogonial cells will be obtained. A sample of fifty cells of each kind will be scored for chromosome number and chromosome aberrations. If alcohol has a cytotoxic effect, the number of chromosomes per cell and/or the number of chromosome aberrations would be increased in bone marrow cells over control levels; if the effect is mutagenic, a difference in chromosome number and/or the number of chromosome aberrations would be expected in spermatogonial cells. The proposed study is necessary to determine the effects of alcohol on the chromosomes of mammalian cells and to show the relationships between cytoxicity and mutagenicity in a mammalian system exposed to ingestible, non-lethal concentrations of alcohol.